Dimethyl adipimidate (DMA) is a bifunctional imidoester which reacts with sickle erythrocytes to prevent hypoxia-induced sickling. We propose to investigate the mechanism whereby this antisickling effect occurs, determine whether there are additional, unfavorable effects upon the erythrocyte, and evaluate potential changes in survival of DMA reacted red cells (both rat and human) in rats. The dose response curve and distribution of 14C dimethyl adipimidate within the erythrocyte membrane and hemoglobin will be correlated with inhibition of sickling, potassium permeability, minimal gelling concentration and oxygen affinity of the hemoglobin. The degree to which crosslinking of the membrane and hemoglobin contribute to inhibition of sickling will be measured in erythrocyte hybrids where only one component of the erythrocyte (either hemoglobin or membrane) will be reacted with DMA. The effects of other crosslinking agents which have different hydrocarbon lengths on sickling will be compared to those observed with DMA in order to determine whether the proximity of the crosslinked groups is critical for the antisickling effect. Possible unfavorable effects of crosslinking reactions on human erythrocytes will be determined by evaluating glycolysis, glycolytic intermediates, permeability, and oxygen affinity. Reaction conditions will be established which minimize toxicity and maximize antisickling effects. Finally, the in vivo survival of DMA reacted cells will be measured in an animal model.